1. Field of the Invention
The present invention relates to dynamic splicing in product lines, and in particular, relates to a double-sided self-splitting adhesive splicing tape.
2. Description of the Related Art
The continuity of production of sheet materials often requires a step of splicing the finishing edge of an active unwinding roll to the leading edge of a new inactive unwinding roll. To continue processing the new inactive unwinding roll, the production line is often temporarily interrupted or even stopped so that the finishing edge of the active unwinding roll and the leading edge of the new inactive unwinding roll can be jointed together by applying a piece of a single-sided adhesive tape. The stopping of the production by such method usually consumes time, and causes a great deal of throughput losses especially when the sheet of the rolls runs at high speeds.
In order to resolve the above issues, some new types of double-sided adhesive tapes have been applied with new dynamic splicing methods while the production continues. Many new corresponding mechanical devices have been developed as well.
Before splicing, one side of the double-sided adhesive tape is attached to the second layer, positioning under the leading edge of the first layer, of the new inactive unwinding roll. The adhesive on the other side are divided into two portions, ready to connect the finishing edge of the active unwinding roll and the leading edge of the inactive unwinding roll. To do so, one portion of this adhesive is partially adhered to inner side of the leading edge of the first layer of the new inactive unwinding roll. The other portion is designed to catch the finishing edge of the active unwinding roll synchronized in a same linear speed. When two rolls are jointed end-to-head together in a dynamic mode, the first layer of the new inactive roll is carried away with tension from the winding roll and needs to be separated from the second layer. Accordingly, a self-splitting mechanism is incorporated in the structures of any of the double-sided adhesive splicing tapes for this to take place. When the first layer and the second layers are separated successfully, the dynamic splicing process is thus completed.
Each new invention comes up with its individual way of achieving such a self-splitting mechanism. The control of the peel forces of the self-splitting mechanism is critical for the success of the dynamic splicing process. These peel forces normally stay lower than the minimum forces required to tear the sheets of the roll while it has to be large enough so it will withstand all the handling processes before splicing.
U.S. Pat. No. 7,152,825 and WO 02/24562 both disclosed ways to achieve such self-splitting mechanism for dynamic splicing. U.S. Pat. No. 7,152,825 disclosed a partially coated adhesive layer while US2002/0056784 A1 or U.S. Pat. No. 6,488,228 disclosed complexity of many layers of coatings with additional barrier coating. Although EP0941954A1 depends on a self-splitting mechanism of a relatively simple, single-layer of non-tacky layer peeled away from the base layer. The uncertainty of physical and chemical nature of the base layer with potentially high porosity usually generates issues for uncontrollable self-splitting and peeling forces. Although the structure have been improved with an additional adhesion control layer in patent U.S. Pat. No. 6,432,241 B1, the self-splitting mechanism still depends on the separation of this coating from the additional non-tacky resin layer.
In spite of the many previous disclosures, the inventions of these splicing tapes remains overly complex in structures with excessive manufacturing processes and difficulty in quality control. The interfacial peel forces control between coating layers becomes very vital but tricky to manage. This is especially pertinent for delicate materials, such as paper.
As mentioned above, most of these products and disclosures depend on the unpredictable nature, splitting the delicate structures at the interfaces between coatings and many substrates. Thus, a novel dynamic splicing tape with a relatively simple but robust self-splitting mechanism which is capable of performing equally effective or better flying splice may remain undiscovered.